I hear ya Cliff. It is, certainly a bit of an exaggeration. More so trying to emphasize brent's role in his years. Though, I think he was number 5 behind Jerry, Bobby, Phil and Bill. (idk if I'd say that for brent).
Anyway though, wanna link me to something particular? Im still mostly a fall 72 head, of which many recordings dont capture keith. 10-21-72 would be one.
While I'd have to agree that Brent's introduction certainly revitalized the band. I'd be surprised if you would not concede Keith's superior musicianship after listening to his contributions during what might have been his peak with the Grateful Dead.